openeuler_defconfig: enable CONFIG_UNICODE for x86 and arm64

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I853Y8



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Enable CONFIG_UNICODE on x86 and arm64 by default to support
the ext4 casefold feature.

Signed-off-by: Baokun Li <libaokun1@huawei.com>